High liquid holdup airlift tower loop reactor: I. Riser hydrodynamic characteristics

Abstract

The hydrodynamics of high liquid holdup airlift reactors have not been widely studied. In this work we study the riser of a reactor of this type, focussing on the in¯uence of the gas¯ow rate and the submergence ratio on various hydrodynamic parameters: liquid circulation velocity, gas holdup, and gas residence time in the liquid. A notable difference in reactor behavior is observed with a submergence ratio equal to unity and with a ratio lower than unity. Correlations for the parameters studied in different conditions, as several submergence ratios, are proposed, these are extrapolations of other equations proposed in the literature for airlift reactors. The reactor studied in this work can be thought of as an element of a great pool formed by multiple elements of similar¯ux type. The studied parameters are shown to be very important for subsequent hydrodynamic and mass transfer modeling of the reactor.

High liquid holdup airlift tower loop reactor: II. Downcomer hydrodynamic modeling

“…The semi‐empirical equations (eqns(1) and 2) describe the liquid descent movement in a simple way. For the riser, we previously obtained the following equation:4 which represents the liquid movement in the riser, since radial homogeneity (high velocities and small diameter of the riser) can be considered here due to the existing turbulence and can be simulated by a plug flow reactor. For downcomer modeling we shall consider as a criterion that the depth which produces a change in CSTR to plug flow reactor behavior is the one which produces 5% deviation between the P dRFP line and P d curve (Fig 4).…”

“…The physical and operating characteristics of the reactor used in this work have been described previously 4. For the present study, a colorimetric tracer method was employed.…”

“…This reactor is considered as a fundamental unit of a great pool formed by many similar elements. In a previous article4, a hydrodynamic study of the riser of this reactor and parameters such as the induced liquid velocity due to gas inlet and gas holdup was carried out. Here, a compartmental model has been developed from the downcomer hydrodynamics, in which different reactor parts are simulated by CSTRs or plug flow reactors, mutually interconnected in a suitable way.…”

Prediction of Riser Gas Holdup in Three- Phase External Loop Air Lift Fluidized Bed Reactor

“…The phase flow rates were measured by calibrated rotameters. Riser gas holdup was measured using the volume dispersion method (Chisti et al 1989, Hwang and Chang 1997, Garcia et al 2000, Bo Jin at al 2006, Yazdian et al 2009. All the experiments were carried out at the room temperature and atmospheric pressure.…”

Liquid velocity in a three and two phase external loop airlift reactors

“…Примењују се за гајење ћелија (животињских и биљних), квасаца и бактерија, при производњи алкалоида, антибиотика, протеина, антитела и многих других супстанци. Њихова примена је такође велика и за уклањање разних загађивача из градских и индустријских отпадних токова [6]. Иако су у најновије време многи истраживачи покушавали да искористе пнеуматске реакторе са рециркулацијом и за хемијску производњу органских једињења [7], ипак је и даље највећа примена ових реактора присутна у биотехнолошким процесима.…”